86431 ÷ 5 = 17286 R1
We're going to perform division on 86431 with 5 as the divisor.

Step 1:
5 goes into 8 1 times with a remainder of 3.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 5 from 8 to get 3.
Bring next digit (6) of the dividend behind the 3 and repeat the process: 36 / 5

Step 2:
5 goes into 36 7 times with a remainder of 1.
Write down 7 as next digit of of the result. 
Result so far: 17
Subtract 35 from 36 to get 1.
Bring next digit (4) of the dividend behind the 1 and repeat the process: 14 / 5

Step 3:
5 goes into 14 2 times with a remainder of 4.
Write down 2 as next digit of of the result. 
Result so far: 172
Subtract 10 from 14 to get 4.
Bring next digit (3) of the dividend behind the 4 and repeat the process: 43 / 5

Step 4:
5 goes into 43 8 times with a remainder of 3.
Write down 8 as next digit of of the result. 
Result so far: 1728
Subtract 40 from 43 to get 3.
Bring next digit (1) of the dividend behind the 3 and repeat the process: 31 / 5

Step 5:
5 goes into 31 6 times with a remainder of 1.
Write down 6 as next digit of of the result. 
Result so far: 17286
Subtract 30 from 31 to get 1.

The final result is 17286 with a remainder of 1.